It is well known to use electro-mechanical slip rings, to enable the transfer of data to and from a rotating device, such as the drum that is rotatably mounted in the gantry of a computer tomography (CT) scanner so that the X-ray equipment supported by the drum can be rotated about a patient during a tomographic scan. However, over long periods of use, mechanical wear and contamination can occur, leading to reduced electro-mechanical contact reliability, possibly resulting in loss of data. Further, where the rotating device is relatively large, such as the drum of a CT scanner, the use of commensurately large slip rings adds significant weight to the total weight of the CT scanner.
In addition, where the rotating device, such as a rotatable drum of a CT scanner, rotates a limited amount with each use, it is also known to transfer data to and from the drum through cables, which are wound and unwound as the device alternately rotates clockwise and counterclockwise. Again, disadvantages include additional weight due to the use of cables, the effects of the attached cables on the rotation of the rotating device, and decreased reliability due to, for example, the vulnerability of cables to disconnection and breakage when the cables are repeatedly wound or overwound.
U.S. Pat. Nos. 4,928,283 and RE 34,379 briefly describe a CT scan system employing a "two-way communication link" between "an electronics package" secured to the disk of the machine and a "computer used for image processing and control". No further detail is provided.